The mechanism by which dimethylnitramine elicits tumor formation in rodents is still unknown. While oxidative mechanisms may be considered, it is possible that a reductive mechanism may supervene in activating dimethylnitramine to carcinogenic metabolites. This possibility will be investigated by subjecting dimethylnitramine and certain other selected secondary and primary nitramines to the Ames mutagenicity assay against mutant strains of Salmonella typhimurium under conditions which favor the enzymatic reduction of the nitramines. The corresponding secondary nitrosamines will also be subjected to these tests under comparable conditions.